Charles Carroll, Barrister was born in 1723 and began construction of his summer home in 1754 on the land known as Georgia Plantation in what was then Baltimore County. Construction of the main block of the house was completed in 1760. Most of the bricks were made right on the plantation grounds. The building was named "Mount Clare" in honor of his sister, Mary Clare Maccubbin, and their grandmother, Clare Dunn Carroll.

The house is Baltimore's only pre-Revolutionary mansion and is one of the finest examples of Georgian architecture in Maryland. It contains an exceptional proportion of possessions of Charles Carroll, Barrister and his wife Margaret Tilghman.

Round House

In 1828, James Maccubbin Carroll, heir and nephew of Charles Carroll, Barrister, offered the newly formed Baltimore and Ohio Railroad a ten acre, hickory treed hill on the northeast corner of his property. In recognition of James Carroll's generosity, the railroad named their new depot Mount Clare Station. This parcel met the need for a route from the north and also proved well-positioned for the rail line south to Washington D.C. begun in 1833.

James Carroll had originally wanted the railroad to cross his land south of the mansion to serve port facilities he had planned for his site on the harbor at the outlet of the Gwynns Fall, but the route suggested by the Army Engineers did not allow this to happen. Since the railroad had to travel in a southwestern direction to reach and ascend the narrow valley of the Patapsco River, the higher route north of the mansion proved more viable. He reluctantly agreed to let the railroad cross to the north of his house.

At Gwynns Falls, the railroad constructed a 312 foot long stone bridge, known as the Carrollton Viaduct, with a single 100 foot long arch. Mount Clare's entrance to the old Frederick Turnpike was cut off, necessitating a new drive south of the house to the new Washington Turnpike, now Washington Boulevard.

In 1830, the B&O Railroad bought another fifteen acres from James Carroll to expand the Mount Clare location. At this time, the Mount Clare shops were actually located in Baltimore County. It was not until 1851 that the City of Baltimore became an independent entity, and annexed this area.

In 1850, James Maccubbin Carroll, Jr., grandnephew of Charles Carroll, Barrister, moved with his family to Monument Street. Mount Clare was then rented to a succession of tenants until the City of Baltimore bought the remaining land in 1890 to create the present Carroll Park.